BigFoot Openhole Whipstock System Reduced ... - Baker Hughes

Case History
BigFoot Openhole Whipstock System Reduced
Costs on Oklahoma Well Drilled in Hard Formation
Well was sidetracked in a few hours, with no cementing time needed
Benefits
• Saved time and trips over
setting a conventional cement
plug for sidetrack
• Saved material costs because no
cementing was needed
Background and challenges
• Independent operator in Oklahoma
• 6 1 /8-in. openhole sidetrack in a
hard formation was required
Baker Hughes solution and results
• Baker Hughes recommended
its 5½-in. OD BigFoot openhole
whipstock system
• The system was run in hole,
oriented, and set in a single trip
• The drilling assembly was run in
hole immediately with no
uncertainty or NPT associated
with cement curing
• A new 6 1 /8-in openhole sidetrack
was created off the whipstock in
the hard formation
On a project in Oklahoma, Baker Hughes saved an
independent operator significant time and money with
its BigFoot openhole whipstock system. The operator
was drilling a production well in central Oklahoma and
needed to sidetrack a 6 1 /8-in. open hole. Traditional
techniques would involve tripping in the well with
drillpipe and setting a balanced cement plug. After
waiting a sufficient amount of curing time for the cement
to harden and set up, a directional drilling assembly
would be run in the hole. Once above the cement plug,
the drilling assembly would slowly time drill off the plug
and sidetrack the well.
Because of hard formations in the area, the cement
plug sidetrack is often not accomplished in the first
try. Multiple cement plugs might need to be pumped
and several drilling attempts made before a sidetrack
is successful. Because of these problems, it could take
several days to execute an openhole sidetrack using a
cement plug.
To save time and cost, Baker Hughes proposed using the
BigFoot openhole whipstock system. This system did not
require cement to be set, and provided a positive kickoff
point by using a steel whipstock face that ensured a high
probability of sidetracking in a single drilling trip.
The BigFoot whipstock system was sent to location and
run in the well. To provide circulation down the work
string while running in hole and orientation of the
whipstock with measurement while drilling (MWD), a
Baker Hughes WindowMaster whipstock valve was
used. This tool allowed circulation to the annulus for
MWD orientation of the whipstock by diverting flow
above the whipstock.
The whipstock was then run through the 6 1 /8-in. open
hole to a depth of 9,120.0 ft (2779.8 m). Once on depth,
the whipstock was oriented by the MWD, and when at
the desired direction, the whipstock valve was closed.
The system allowed for pinpoint accuracy of sidetrack
depth and direction.
Run in hole
Set position

The 5½-in. outside diameter (OD) BigFoot anchor was then
set with hydraulic pressure, securely anchoring the whipstock
assembly in the openhole formation. It did not require a bottom
in the wellbore to anchor the whipstock. The running tool was
then sheared off and the work string pulled out of the hole,
leaving the whipstock at desired kickoff point depth. A clean
face was left downhole with no steel lug to mill off.
A 6 1 /8-in. directional drilling assembly was then tripped in hole,
above the whipstock. The openhole sidetrack in the hard formation
was then achieved by time drilling off the whipstock face that
provided a positive deflection point.
Complete openhole whipstock operations lasted only 19 hours.
Of those 19 hours, only one hour was spent on bottom orientating
and setting the BigFoot openhole whipstock system. After that,
the directional assembly was run to sidetrack and drill the lateral.
This represented significant drilling cost savings for the operator
and removed uncertainty and delays associated with cement plugs
from the operation.
The Baker Hughes openhole whipstock system features a lugless open face that
promotes positive displacement from the original wellbore.
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